Why the hell people add me on LinkedIn for like no reason? Why do people do that?

I mean, "John Doe wants to connect". Ok, let's see, maybe I know him... "John Doe, Chemical Engineer living in Argentina"

WTH man? I don't know you, I don't work with chemicals, I don't live near Argentina, and we do not have anyone in common!

Unless you're a recruiter; if I don't know you and you don't specify why you wanna connect with me, I'll ignore your request.